PCA was set at a fixed dose (fentanyl, 0.05 mg/kg loading dose and 0.03 mg/min/kg continuous dose) to remove the effect of a variable amount of PCA. VAS pain score, IL-6, cortisol, IL-1beta, IL-8, and substance p, were checked 1, 6, 12, 24, and 48 hours postoperatively. VAS pain score was selected from 0 to 10, with 0 being no pain and 10 being the most severe pain that the patient had ever experienced.